Power miter saws, also known as chop saws or drop saws, are typically used in framing, molding operations, or other machining or carpentry to cut lumber, trim, metal, and other work products. Wide workpieces, such as crown molding and the like, often require a miter saw with either a large saw blade or a configuration that enables the blade to be moved along a horizontal path away from and toward the fence of the miter saw. Such blade moving configurations are generally referred to as sliding compound miter saws.
In order to accomplish the horizontal sliding movement of the saw blade, some conventional miter saws include a sliding guide assembly that has a linear guide, which typically includes two bushing and rod combinations. These relatively expensive linear bearings consist of recirculating ball bearings that operate together with turned, ground, polished, and hardened steel rods that are approximately 40 cm long and 30 mm in diameter. To have minimum play and deflection of the saw blade and motor assembly, precise fits are required between the rods and the linear recirculating ball bearings over the entire linear travel of the rods. Additionally, the rod must be made of steel having high hardness to prevent the hard steel balls from making indentations in the rod. As a result, the sliding guide assemblies are heavy and expensive to manufacture.
An additional undesirable feature of such bushing and rod linear guides is that space must be provided behind the saw for the rods to extend when the saw blade is positioned in its rearmost position, near the fence. Because of this space requirement, a sliding miter saw cannot be positioned such that a wall is immediately behind the base. Consequently, the saw occupies a larger footprint.
Moreover, these bushing and rod linear guide mechanisms are susceptible to damage from dirt and debris. Dirt and debris can penetrate into the ball bushings and damage the bearing. In some saws, the rod and bearings are covered with a bellows or similar cover. However, the dust and debris produced by a saw, particularly in metal cutting saws, typically leads to degradation of the fabric of the bellows and penetration of the ball bushing by the abrasive particles.
Some other conventional miter saws include a hinge assembly having two hinges. One hinge is configured to fold vertically and maintain the lateral position of the saw blade, while the second hinge is configured to fold horizontally and maintain the vertical position of the saw blade. The combination of the two hinges enables forward and rearward movement of the saw blade while restricting vertical and lateral movement.
In some saws, the horizontal hinge is configured to fold outwardly relative to the plane of the saw blade. However, the outward extension of the hinge when in the retracted position, wherein the saw blade is nearest the fence, interferes with the beveling of the saw in the direction of the hinge extension. As a result, a saw having an outwardly extending hinge is typically only able to bevel in one direction, namely the direction opposite the extension of the horizontal hinge.
In other saws, the horizontal hinge is configured to fold inwardly, across the plane of the saw blade. In order to avoid interference between the vertical and horizontal hinges, the hinges must be arranged in line with one another along the sliding direction of the saw blade. For example, the horizontal hinge is typically configured to fold under the vertical hinge. However, since the horizontal hinge is positioned under the vertical hinge, the vertical hinge cannot fully retract. The in-line arrangement of the hinges requires additional space behind the saw blade, and results in more parts in the hinge assembly.
What is needed, therefore, is a miter saw that is more compact, lighter weight, and more portable than conventional miter saws.